5th Dryland Agriculture

7/31/2019 5th Dryland Agriculture

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w y l er d epa r t m en t o fd r y l a n d a g r i cu l t u r e

Dryland lanscaping

with cacti and

succulents

minimizes water

consumption.

Clockwise from upper left:

Amaryllis (Hippeastrum)

grown in the Negev are

exported to European

markets.

The extensive root system

of Schismus arabicus Nees

(Poaceae) enables the plant

to survive and to colonize

between rainfall that

engenders germination

until the next rainfall, even

if this period lasts for as

long as two weeks.

Intercropping: Feed crops,

planted betweenAcacia

saligna trees and irrigated

with runoff water in an

experimental field.


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Runoff water can be directed to

agricultural fields for improved

dryland agricultural production.

Wy l er Depa r t m en to f Dr y l a n d Agr i cu l t u r e

Dr. Pedro Berliner, Chairperson

The Wyler Department of Dryland Agriculture develops technologies for improving

agricultural practices in drylands, which cover approximately a third of our planets land areaand are populated by some 1.8 billion people. The socio-economic conditions and theclimatic and edaphic (soil) factors prevailing in these areas vary greatly. The agriculturaldevelopment strategies for various types of arid regions must therefore be individuallytailored. In addition, dryland ecosystems are extremely fragile and the introduction of newagricultural activities may affect local biodiversity, leading in the long run to desertification. Itis therefore necessary to elaborate new approaches to agricultural development that takeconservation of biodiversity into account.

Worldwide, dryland agriculture is generally rain-fed. Because of low precipitation, specialfarming techniques and well-adapted crops are needed to ensure successful, stable andsustainable agriculture. An appropriate, interesting and sophisticated 2000-year-oldtechnique was studied and refined in our department: the harvesting of water foragroforestry systems that provide firewood and fodder, two important commodities in thearid zones of developing countries. Runoff generated during rainfall events flows bygravitation into the lower-lying parts of the landscape and is retained in walled plots. In theseplots crops are planted and have an adequate water supply. The advantages of this irrigationsystem are that it is cheap, simple to implement, and does not require a sophisticatedinfrastructure. Some of the more specific topics we are dealing with are optimizing plantingdensity, soil amendments, mulching, supplementary irrigation, irrigation with brackish water,efficiency of runoff production and the implementation of agroforestry systems.

In extensive dryland agriculture, animals are an integral part of the production system. Their

fodder requirements can be met by the production of fodder in the previously describedsystems. However, runoff agroforestry cannot be implemented everywhere. Drylandfarmers are traditionally pastoralists, using livestock grazing on noncultivated areas, includingrunoff-contributing slopes. Where runoff agroforestry cannot be implemented, livestockgrazing is the only source of sustenance. Understanding the interaction between animals,native plant population communities, and the physical structure of the landscape as affectedby human land-use is critical to ensuring the sustainability of pastoral systems. Our workinvolves extensive basic and applied studies in plant and animal physiology, animal nutrition,plant population dynamics and biodiversity, rangeland ecology, agricultural physics, and soilfertility and chemistry.

In some areas, capital and infrastructure are available and they allow the introduction ofextremely sophisticated intensive production systems. The introduction of greenhouses inarid regions has allowed farmers to market their produce very early in the season, therebyincreasing their incomes. The development of appropriate greenhouse managementtechniques for arid zones requires the understanding of the complex interactions betweenthe external and the internal climate of the greenhouse and the response of the crop tothese changes. Moreover new fertilization techniques have to be devised in order tocapitalize on the potential advantages of the system. We are intensively studying methods ofcontrolling the growing environment in greenhouses to optimize agricultural production anddeveloping techniques to grow flowering bulbs, exotic cacti and other crops for marketingabroad.

Brackish water is frequently available in arid zones and its use may help improve theeconomics of dryland agriculture. We are studying the long-term consequences of irrigationwith brackish water and its effect on various field and greenhouse crops, paying special


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A f t er r i pen i n g r a i n

r eq u i r em en t s f o r

g er m in a t i o n a n d

seed l i n g d r o u g h t

t o l e r a n c e o f w i l d ba r l ey

Gu t t er m a n

attention to the changes in soil properties due to the use of brackish water.In addition to the laboratory facilities at Sede-Boqer, the department has two experimentalfarms: the runoff-farm in Wadi Mashash and the Even-Ari Farm for Ecology and RunoffResearch in the Desert at Avdat. The latter is one of the ILTER (international long-termecological research) field sites for studies of rangeland ecology and management at the lowend of the rainfall range (in cooperation with the MDDE).

The Katif Research Center for the Development of Coastal Deserts is a regional R&D centeraffiliated with the department.

Phone: 972-8-659-6758 Fax: 972-8-659-6757 E-mail: [email protected]

A ca d e m i c st a f fBen-Asher, JiftahBerliner, PedroBoeken, BertrandDegen, Allan A.Ephrath, Jhonathan E.Gutterman, YitzchakSilberbush, Moshe

A sso c i a t e St a f fCarmi, GenadiChauser-Volfson, Elena

RESEA RCH A CTI V I TI ES

Ec o p h y s i o l o g y

Wild barley (Hordeum spontaneum) is a winter annual grass found in the Irano-Turaniansteppes, the Saharo-Arabian desert, and the Mediterranean region. Because the smallamounts of rain required to trigger germination may be followed by long dry periods, theability of young seedlings to dehydrate, survive until the next rainfall, and recover their abilityto grow and develop new roots, is vital for survival. The survival strategies of dried seedlingsof H. spontaneumwere studied in the laboratory. We found that the percentage of driedseedlings that developed normally depended significantly on their genotype, root length, andthe length of the period of drought. We also found that there are great genetic differencesamong local genotypes from the same general area. There are even differences within oneplant population, and among patches of plants that grow on different types or depths of soilin a particular location.

As part of a research project financed by the DIP Foundation, 150 hybrids, totaling morethan 200,000 plants, are being grown at Sede-Boqer under water stress conditions of about130 mm/season with a control area receiving the equivalent of 350 mm of water per seasonin 4 replicates. These hybrids are derived from crossing cult ivated barley Mona, which is notdrought resistant, with Hordeum spontaneum genotypes from Sede-Boqer and Wadi Kelt,which are highly adapted to drought. Ecophysiological features are being studied todetermine the genetic segregation and combinations with the highest drought tolerance.These features include branching, flowering, plant biomass, seed yield, seed afterripening andseedling drought tolerance of future generations.With: E. Nevo, Haifa University; P.Neumann, Technion Israel Institute of Technology; D. Yakir, W eizmann

Institute; Z. Eyal, Tel Aviv University

Pteranthus dichotomusForssk

(caryophylaceae), one of the most

salt-resistant annuals in the N egev

highlands, emerging on loess soil.


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Co m p l e m en t a r y set s o f

su r v i v a l st r a t eg ies i n

o n e o f t h e m o st co m m o n

a n n u a l p l a n t i n t h e

N e g ev Sch ismu s a r a bicu s

Gu t t er m a n

Ger m i n a t i o n i n h i b it i o n

b y so i l s o f t h e N eg ev

Deser t

Gu t t er m a n

D y n a m i cs o f t h e

a b u n d a n c e a n d i n c i d en c eo f a n n u a l p l a n t sp eci es

d u r i n g co l o n i z a t i o n

Bo eken

During 1999 we studied two more fascinating survival strategies of the complex alreadystudied in the past: 1) The phenotypic germination plasticity of Schismus arabicusaffected byseed size. On young plants more large seeds (caryopses) mature and on older plantsrelatively more small seeds mature. The larger the seeds, the faster their germination, andthe wider the range of temperatures required for germination; 2) Seedling drought tolerance(point-of-no-return). It has been found that roots of young Schismus arabicusseedlings, even

if they reach the length of over 20 mm, can survive after a drought of up to 30 days andcontinue to grow into normal plants. Such a unique phenomenon has not yet been found inany other desert plant.

In this study we found that soil factors inhibit seed germination and affect the distribution ofplant species in desert environments. We studied the inhibition of Plantago coronopusseedgermination in petri dishes on cyanobacterial soil crusts and on soils collected from belowshrubs in the Negev desert. Soil samples originated in regions along the annual rainfallgradient from 50-325 mm/year. We found that germination inhibition is greater on soils fromareas receiving higher than average annual rainfall and on soils with higher total carboncontent. Moreover, the higher the average rainfall and the thicker the soil crust (from 1 to15 mm), the stronger the inhibition of germination. We also observed that along the rainfallgradient investigated, the amount of carbon in the soil samples was higher in samples fromareas with higher rainfall. The relationship between soil carbon and germination is not yetunderstood, but there is a clear correlation between the amounts of carbon in the soil crustand the inhibitory effect along the rainfall gradient. Germination inhibition and its control bysoil carbon content may be important for the distribution and dominance of plant species inthe Negev desert.With: M.Shachak, E. Zaady, BIDR

Ra n g el a n d Veg et a t i o n Ec o l o g y

The colonization of annual plants in small-scale disturbances and undisturbed soil was

investigated for four years in the northern Negev desert. The experiment consisted oftwenty-four 1/m2 patches: eight undisturbed patches; and eight 30 cm-deep pits and eight 20cm-high mounds, from which the seed banks were removed. Annual rainfall varied from97.5mm to 283.0mm. For each of the ca. 100 species, abundance (the average local densityin patches occupied by the species), and incidence (the proportion of patches occupied)became stronger with time. A few species rapidly colonized all patches with their abundanceincreasing exponentially over the years of study; these species were hardly influenced by thevariations in rainfall. Most of the species, however, experienced frequent local extinctions,colonized in few patches, and responded strongly to rainfall. The incidence and abundancevalues of the species, and their changes in time, signify constraints on local populationgrowth, on colonization, and on population persistence. We found that the less commonspecies in our experiment had incidences and abundances that varied strongly with rainfall.This indicates a site-dependent limitation of local populations and their spatial distributions.Some species may be limited by dispersal, in conjunction with their dispersal mode, and bypatch-specific seed capture. In contrast, the common species have weak constraints andexperience density-independent population growth, which is only seed-limited. Inconclusion, determination of abundance/incidence data is a useful tool for investigatingassemblage dynamics.With: M. Shachak, BIDR


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Co l o n i z a t i o n o f a n n u a l

p l a n t s i n a n

ex p er i m en t a l l y a l t er ed

d e ser t l a n d sc a p e

Bo eken

Resp o n ses o f a n n u a l

p l a n t co m m u n i t i es t o t h e

d en si t y o f sm a l l - sca l e

so i l d i st u r b a n c es

Bo eken

Th e r o l e o f pa t ch y l i t t er

d i st r i bu t i o n i n d r y

s h r u b l a n d s

Bo eken

In order to determine how plants colonize in shrublands, we compared the colonization byannual plant species in a natural landscape and in experimental patches. We prepared eightsets of experimental patches consisting of pits and mounds, clearing them of vegetation, soilcrust and the existing seed bank. In the first growing season, a similar number of speciescolonized both pits and mounds in the experimental patches. However, the total number ofindividual species was higher in the pits than on the mounds. Most of the early colonizing

species became resident in the patches, but some colonization of new species occurredduring the second year. From the second year on, adjacent natural patches of undisturbedcrusted soil were also colonized, primarily from experimental pits and mounds. Weconcluded that the ability of patches to support colonization (the so-called sink function)increases with removal of vegetation, soil crust, and the existing seed bank. Our experimentsshow that the sink function of pits and mounds represents a powerful tool for linkingvegetative communities and landscape processes.With: M. Shachak, BIDR

The effect of the density of small-scale experimental soil disturbances on plant diversity andproductivity were investigated. In our study, we used soil diggings (similar to foraging diggingsmade by porcupines) from four densities. In the spring of three years, we measured plantdensity, species richness, and plant productivity in the diggings and in adjacent, equal-sized,undisturbed control areas. We found that: 1) annual plant community parameters werehigher in the diggings than in the adjacent undisturbed matrix; 2) these parameters decreasedin the diggings as digging density itself increased, but not in the undisturbed matrices; 3) inthe last year of study, seed densities captured in the diggings from outside the digging,decreased with increasing digging density; 4) at the highest digging density, there was nodown-slope decline of plant density and species number in the diggings, as would beexpected if intercepting runoff flow was responsible for the digging-density effect. Theadditional resources and seeds in diggings increased plant density, as well as species richnessand productivity, relative to the undisturbed matrices. However, the contrast between thediggings and the undisturbed matrix diminishes at higher digging densities, indicating that

when in close proximity, the beneficial effects of the diggings are canceled out. The lack of adown-slope effect indicates that the interference is due to interception of the wind-driven,nondirectional flow of seeds.With: N. van Rooyen, University of Pretoria, RSA

The effects of litter on the distribution and flow of water, soil and organisms (annual plantsand termites) in shrubland ecosystems were investigated in experimental units containing acrust and a shrub patch. Leaf litter was added in single or double quantities to either, bothor neither of the patches. The variables measured were surface water runoff, seedlingdensity, and the biomass and species richness of annual plants. Litter addition decreasedrunoff, regardless of the location or amount of litter applied. Litter on the crust increasedseedling density of sparse species, but not of dense species. Adding a double litter layer tothe crust increased biomass and species number, while the single layer had no effect. Litteraddition to the shrub patch affected neither biomass nor species richness. Litter addition toboth patches at both levels caused a large increase in termite activity. Termites turned overtopsoil and disrupted the crust, which may reduce runoff and, via seed flow, alter annualplant biomass and richness. On the crust, annual plant productivity and species richness arelimited, because few structures are available to stop the outflow of water, soil and seeds.Shrub patches which already had litter were not affected by the additional litter. Production,accumulation, and patchiness of lit ter can have considerable impact on landscape-wide annualplant productivity and diversity, and should be viewed as important factors in shrublandmanagement.With: M. Shachak, BIDR

Measuring plant responses in

small-scale soil disturbances.


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D ev e l o p i n g t ec h n i q u es

f o r r a i si n g ca c t i f o r

l a n d s c a p i n g

Gu t t er m a n

Lea f b a r b a l o i n

v a r i a t i o n a s a n a n t i -

b r o w si n g per i ph er a l

d e f en se st r a t eg y o f

Al o e a r bo r escen s

Gu t t er m a n ,

Ch a u ser -Vo l f s o n

O pt i m i z a t i o n o f

a m a r y l l i s (Hi ppea st r u m)

b u l b pr o d u c t i o n

Ben -A sh er , Eph r a t h ,

Si l ber bush

Th e ef f e ct o f sa l i n i t y o n

co r n y i el d u si n g t h e

Ce r e s- m a i z e m o d e l

Ben -Ash er

Pl a n t Ph y si o l o g y a n d Cr o p Dev el o pm en t

A combination of lighting conditions, soil treatment, irrigation regimen, and a novel methodof pruning has enabled us to produce ornamental cacti with an improved ability to send outperipheral branches. The new technology reduces the time necessary to obtain a marketablecommodity and decreases the costs of production. In addition, production rates under

greenhouse conditions are favorable as compared to conventional approaches. (Funding:Rashi Foundation).

Barbaloin, which is a secondary phenolic metabolite, is apparently distributed in Aloearborescensas a peripheral defense strategy. We found that the youngest leaves have thehighest barbaloin content. The more times a leaf is cut, the higher the barbaloin content inthe new growth that sprouts from the leaf base that remains on the plant. This may deteranimals such as elephants and kudu from eating the new growths. This may allow damagedplants to renew themselves before their leaves are eaten again. Secondary metabolites arewidely used in the medicinal and cosmetic industries. We plan to use Aloeplants with thehighest potential as a new crop for supplying metabolic compounds to these industries. Thisspecies grows very well in the Negev, is easy to propagate, and requires very little water tothrive; Aloeis, therefore, an ideal crop for kibbutzim and other farmers in southern Israel.Dramatic progress was made during 1999 when we found that the three or even foursecondary phenolic metabolites (SPM) are distributed in relative amounts to the amount ofbarbaloin in the leaves. These act as a cocktail of defense materials that may preventmutations of the plant consumers such as insects.

In a seven-year study we tested agrotechniques, the economics and storage aspects ofgrowing Amaryllis (Hippeastrum) plants, which produce a cross-shape cluster of four flowers,for blossoming during the Christmas season as an export crop. W e also developed aneconomical method for raising virus and disease-free bulbs suitable for export.The techniques resulted in a reduction of the growth period from two and-a-half years to

one year, and a change in the flowering time from May to the Christmas season. Weachieved a considerable savings in production methods, especially in heating the soil, with aninnovative heating method and by controlling surface temperatures of the soil. Changes inamount and make-up of fertilizers led to a rise in the rate of bulb growth. Raising theconcentration of CO2 in the greenhouse reduced the need to heat the soil and increased therate of bulb growth. We fertilized the crop by means of drip irrigation lines with alternatingcapacities so that they provide an identical amount of water and varying amounts of fertilizer.Virus-free bulbs were developed by propagating tissue culture from virus-free materialsimported from overseas. (Funding: Rashi Foundation).(Also, see below, Katif Research Center for the Development of Coastal Deserts)

The Ceres-maize model, used by agricultural experts to estimate corn yields, simulates theeffects of plant genotype, weather, and soil properties in order to predict harvests. In mostcase, when calculating water availability, soil water is taken into consideration, but the effectof soil salinity on plant wilting is neglected. A revised model takes account of this formerlyoverlooked problem. It showed that nitrogen fertilization increases the salinity thresholdvalue (the maximum average salt concentration in the root zone that does not reduce yield)and the sensitivity of yield to salt salinity. It also showed that forage corn is more sensitive tosalinity than is grain corn. In soil that is not leached, the heavier soil texture results in ahigher salinity threshold value, but if it is leached, soil texture has no influence on the salinitythreshold. In sandy soils, the yield is less sensitive to salinity.


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M o d e l i n g o f n u t r i en t

u p t a k e a n d sa l t b u i l d u p

i n so i l l ess c u l t u r es a n d

h y d r o p o n i c s

Si l ber bu sh , Ben -Ash er

Th e r el a t i v e ef f i ci en c y o f

so i l v s. f o l i a r N PK

f er t i l i z er s f o r m a i z e

g r o w t h

Si l ber bu sh

P h y s i o l o g i c a l

Ch a r a c t er i z a t i o n o f

St r a w b er r y Cu l t i v a r s

w i t h D if f er en t i a l

Su sc ep t i b i l i t y t o I r o n

D e f i c i e n c y

Si l ber bu sh

Co r r el a t i o n b et w e en so i l

ch a r a c t e r i st i cs a n d

t h ei r r ef l ec t ed sp ect r u m

Si l ber bu sh

Resp o n se o f Aca cia

sa l i gn a t o i r r i ga t i o n

w i t h b r a ck i sh w a t er

Ber l i n er , Eph r a t h

Growth of cash crops in modern agriculture requires intensive plant growth with precisemanagement in artificial and hydroponic cultures. Yet, high inputs of fertilizers and salinitybuildup due to transpiration by plants might introduce an environmental risk of soil andgroundwater chemical contamination. A dynamic model was developed to predict theperformance of a hydroponic system with nutrient solution and plant growth. The modelcan predict the rate of nutrient uptake by the plants, the change in chemical composition

of the solution including salt accumulation, and the efficiency of liquid fertilizer amendment.

Nutrient uptake by plants from soils is sometimes restricted because of the soilcharacteristics and plant adaptation. Foliar fertilization was suggested as an alternative wayfor plants. Two commercial foliar fertilizers were compared to mineral forms of the majornutrients nitrogen (N), phosphorus (P) and potassium (K). The fertilization was appliedeither to the soil or to the leaves of maize plants grown in pots with the typical desert soilof Sede-Boqer. The trial indicated that plants more effectively absorb nutrients from thesoil via their roots than via their leaves. Yet, combining soil and foliar fertilization mayimprove plant nutrition more than by using each method alone.With: Fan-Ling, Ben-Gurion University

Strawberry genotypes vary widely in their sensitivity to leaf chlorosis caused byiron-deficiency when grown in calcareous soils. Five cultivars, originated from California,Turkey and Israel, were tested in a nutrient solution culture with deficient and sufficientlevels of iron for their uptake efficiencies. There was a correlation between the genotypicsensitivity and leaf iron and chlorophyll contents in iron-deficient plants. The hypothesisthat these differences are due to organic acid exudation by the roots (phytosiderophores)is currently being tested. The results of this study show how strawberry plants overcomeiron deficiencies. These qualifications may be introduced into high-quality cultivars that aresensitive to lime-induced chlorosis when grown in calcareous soils, either bycross-breeding, gene-transfer or by fertilization.With: Yasa-Faskas, Chukarova University, TUrkey

To test the usefulness of remote sensing as a tool to map soil surface, a series of soils weresampled along the Zikim (semi-arid, Mediterranean) -Beersheva (arid, desert ) transect. Thesoils were characterized for texture, color, and contents of organic matter, iron oxides andcarbonates. For comparison, these soils were surveyed by X-ray defraction for mineralcontents. High correlation was obtained between soil color components and theirreflectance. Soil moisture was correlated with the reflectance at 1900 nm; Iron oxidecontent was best correlated with (in decreasing order) 1986 and 1373 nm; Organic mattercontent with 2200 and 1402 nm; calcium carbonate was best correlated with reflectance at1746, 1912, 1743, 1714 nm. It was concluded that these soil properties could be quantifiedby their reflectance spectra using remote sensing techniques.With: D. Blumberg and B. Kelhamer, Ben-Gurion University

The effects of the interactions of irrigation at three frequencies (twice a week, once a weekand twice a month), water quality (1 and 6 dSm-1) and simulated runoff application duringwinter on the productivity of Acacia salignawere evaluated for the fifth consecutive year.Cross sectional area of trunks (CSA), predawn leaf water potential, transpiration (using thesap flow technique), nondestructive monitoring of root development (using theminirhizotron), water uptake patterns, salt distributions in the soil profile and soil surfaceproperties were monitored throughout the whole year. The shrubs were pruned inOctober and November to determine yields of the various components. Allometricequations were derived and compared to those obtained for the same species at differentlocations. It appears that irrigation frequency affects the biomass/CSA correlation. The

plots irrigated with brackish water began to show a significant decrease in biomassproduction. A detailed statistical analysis is presently being carried out.With: E, Garcia and W. Zegada, Ben-Gurion University


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Fi el d m o n i t o r i n g r o o t

d e v el o p m en t u si n g t h e

m in i r h i zo t r o n t ech n i q u e

Eph r a t h , Si l b er b u sh ,

Ber l i n er

Ev a p o t r a n spi r a t i o n o f a

r o w c r o p ir r i ga t ed w i t h

b r a ck i sh w a t e r

Ber l i n er

I m pr o v ed b r eed i n g

o f o st r i ch e s

Degen

A n i ma l h u sb a n d r y

i n t h e d e ser t

Degen

Roots, often referred to as the hidden half of plants, play a key role in crop development andadaptation to harsh environments. Understanding root dynamics is important forunderstanding how crops grown on stored water interact with the environment and, inparticular, for explaining the observed competition between species, as is the case in a runoffagroforestry system. Conventional root sampling techniques, such as coring, are destructiveand require a large number of replicates in order to follow the development of a complex

root system. Such labor-intensive work is not always feasible. The minirhizotron system is aviable and promising alternative for root studies. Root growth and development is followedalong a clear tube inserted in the soil and is recorded with a miniature video-camera. Inorder to implement this technique the immediate surroundings of the clear tube must berepresentative of the bulk soil. This key issue is presently being evaluated.

The estimation of fluxes above crops planted in rows presents several problems, the mostserious one being to find the minimum height above which there is horizontal homogeneity.We built a multiple height Bowen ratio machine and carried out a series of measurementsabove a tomato crop grown in the field and irrigated with locally available brackish water.

The results indicate that the minimum height depends on the direction of flux and windspeed. The computed evapotranspiration indicated that the field was being over-irrigated.With: P. Figuerola, University of Buenos Aires, Argentina

An i m a l Ph y si o l o g y a n d H u sba n d r y

In order to improve ostrich breeding in the Negev, a lighting regime was developed thatincreases female ostrich fertility. By providing additional lighting during the breeding season,hens produced greater numbers of eggs of which a larger proportion were fertile. A methodfor collecting ostrich semen based on sexual starvation was designed. Using this system,semen collected from a number of ostriches was evaluated for quality, the number ofabnormal sperm, and pH levels. Improving the preservation and storage of ostrich semen isbeing pursued in order to make possible art ificial insemination. Studies of the hormonal basisof female ostrich fertility is under study in order to identify ostriches with a high breedingpotential. (Funding: Rashi Foundation).

Projects dealing with improving techniques of animal husbandry in the desert include: 1) thedetermination of optimal water temperature for relieving stress in poultry raised in thedesert; 2) the use of legume trees and shrubs as fodder for sheep and goats; and 3) cattleraising and marketing by the Maasai in Kenya. (Funding: NetherlandsIsrael ResearchProgram).

Below and right: Acacia roots

photographed using

minirhizotron technique.

Roots with nodules: #1 before and

#2 after a flood. In #2 the black

color shows destroyed nodules.

#1 #2


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m et a b o l i sm a n d

r epr o d u ct i o n o f w i l d

d eser t a n i m a l s a n d b ir d s

Degen

Wa t er r el a t i o n s a n d

p h o t o s y n t h esi s o f A ca c i a

sa l i gn a u si n g r u n o f f

i r r i ga t i o n i n a n a r i d

z o n e

Eph r a t h , Ber l i n er

Co o r d i n a t ed u se o f

m a r g in a l w a t e r i n a r i d

r eg io n s

Ber l i n er

W a t e r b a l a n ce o f

sel e ct ed c o m p o n en t s o f

t h e A u r o v i l l e w a t e r sh e d

i n I n d i a

Ber l i n er

Investigations of desert mammals and birds deal with: 1) field metabolic rate andreproductive success in free-living mammals (supported by the U.S.-Israel Binational ScienceFoundation); 2) the cost of reproduction in desert rodents; 3) the fat sand rat as a newtourist and educational resource in the Arava valley (supported by the Israel Science Fund);and 4) energy expenditure and water flux in free-living Arabian babbler birds (Turdoidessquamiceps). (Funding: Israel Science Foundation).

Wa t er H a r v est i n g a n d A gr i cu l t u r a l Ph y si cs

Water harvesting can be used to cultivate crops in areas that would otherwise yield onlymeager and sporadic harvests. Since global food production must double during the nextcentury, it is essential to examine the possibility of expanding the use of arid and semiaridregions for farming. Sparse precipitation in dry regions is not the only factor limitingagriculture, for soils in these areas are usually unstable and prone to crusting as a result ofrainfall. Water infiltration into the soil is, therefore, severely reduced and runoff isgenerated. If the runoff is conveyed to low-lying areas, trapped in dyke-surrounded plots, orallowed to form ponds, such plots can be used for agriculture once the water subsides.

Understanding the physical processes involved in the generation and transport of runoff andthe biological processes that determine the efficiency with which the stored water is used byannual and perennial crops is crucial for the successful implementation of runoff desert farming.

A five-year study was undertaken to investigate the water relations and photosynthetic rateof Acacia salignaunder various levels of water availability. Biomass production and water-useefficiency (the ratio of biomass produced to water used) were characterized under variousrunoff irrigation regimes. During two seasons, water relations, photosynthetic rate, stomatalresistance, leaf-water potential, osmotic potential, and biomass production were examinedfor two situations: 1) well-watered (control treatment, irrigated every two weeks); and 2)water-stressed treatment, with no irrigation throughout the growing season. Preliminaryanalysis of the data indicates that the trees appear to adapt to water stress.

The possibility of supplementing erratic runoff water with brackish water is beinginvestigated. Field and pot trials have been carried out that measure the effects ofgood-quality water, brackish water, and a combination of brackish and good-quality water onAcacia salignadevelopment. The influence of fertilization on biomass production has alsobeen evaluated. The results obtained from pot trials indicate that salinity stress can bemitigated with appropriate fertilization. Field trials indicate that the effect of salinity onbiomass is minor, if at all present.With: S.H. Lips, BIDR; and J.O. Nyabundi, Maseno University College, Maseno, Kenya

The rational use of available rainfall and aquifer water relies on the knowledge of the input

and output of the water system as a whole. Quantification of the different fluxes(transpiration, evaporation from the soil, runoff, drainage into the water table, etc.) requiresa multidisciplinary approach, involving hydrology, soil physics, agrometeorology, and plantphysiology. The following aspects are under study in Auroville: 1) transpiration of selectedtree species using the heat-pulse technique; 2) water-table recharge; and 3) the effect ofwater availability and climate on water use by the tree species being investigated.With: A. Greaves, Auroville Sustainable Development Center, Tamil Nadu, India

Acacia saligna growing inrunoff pond.


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W a t er a n d CO 2 c y cl i n g i n

d eser t en v i r o n m en t s

u s i n g st a b l e i so t o p es

Ber l i n er

Est i m a t i n g t h e ef f ec t o f

d ew o n f i e l d w a t er

b a l a n c e s

Ber l i n er

Using conventional micrometeorological techniques and isotopic measurements, we areattempting to estimate the fluxes of carbon dioxide and water in the atmosphere above arunoff agroforestry system. The use of isotopes allows us to partition the net fluxes intotheir components and is easier to implement than the micrometeorological approach.Measurements carried out over a number of crops seem to confirm the superiority of theisotope approach.

With: D. Yakir, Weizmann Institute of Science

Dew provides a major part of the water supply in the Negev highland, accounting for abouthalf of the total precipitation. Few measurements have been carried out to determine theamount of dew absorbed by soil and the energy fluxes involved. Extremely sensitivemicrolysimeters (soil moisture measurement devices) coupled with one-dimensional sonicanemometry (air speed measurement) and a Bowen ratio system are being used to quantifyand parameterize these fluxes.

One of the 120 species of Aloe

introduced from South Africa.

These plants are well-suited for

landscaping in dryland gardens.


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Ka t i f R esea r ch Cen t er f o rD ev el o p m en t o f Co a st a l D eser t s

Prof. Jiftah Ben-Asher, Director

The Katif Center is located in a region of coastal desert on the Mediterranean Sea. TheCenters research focuses upon issues of climate, soil and water that are unique to coastal

deserts. In heavily populated areas, where shallow fresh water aquifers and meager soilresources may be depleted and/or contaminated, agricultural production must be carefullycontrolled. The main goals of researchers at the Center are to develop sustainableagricultural techniques for the purpose of enhancing Israels agricultural production, and todevelop new agricultural products in the Katif region.Established as a regional R&D facility in 1984 by the Ministry of Science and Technology, theKatif Research Center is an extension of the BIDRs laboratories; farmers and scientistswork together to develop practical, economic applications from laboratory investigations.The research is carried out by eight permanent, full-time staff members, five part-timemembers and ten scientific consultants from other research institutions in Israel (includingthe Faculty of Agriculture of the Hebrew University of Jerusalem, the Agricultural Research

Organization (ARO) and the Technion, Haifa). Research project leaders serve as consultantsin projects related to their fields of expertise.

Our research focuses on the following areas:! Improving agricultural practices in the Katif Region.! Studying desertification causes in coastal deserts and prevention methods.! Developing new agricultural and ecological approaches.

Phone: 972-8-684-7477 Fax: 684-7565 E-mail: [email protected]

A ca d e m i c St a f fBen-Asher, JiftahEphrath, Jhonathan E.

A sso c i a t e St a f fAlekperov, ChingisBrikman, Vladimir

New agrotechnigues for growing

Amaryllis (Hippeastrum) resulted

in reduced growth period, and

change in flowering time from

May to December.

Its cross-shaped flower clustermakes it an ideal export crop for

market ing during the Christmas

season.


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Fl o w e r i n g Bu l b s

I m pr o v e d Pr o d u c t i v i t y

f o r Gr o w i n g Veg et a b l e s

i n Gr een h o u ses

I n se ct - f r e e

Gr een h o u ses w i t h a

m i n i m u m o f p est i c i d e u s e

Cl i m a t e co n t r o l

i n g r een h o u ses

I d en t i f y i n g Eco l o g i ca l l y

So u n d A gr i cu l t u r a l

Te ch n i q u e s

Im pr o v i n g Ag r i cu l t u r e i n t h e Ka t i f Reg io n

Amaryllis (Hippeastrum) bulbs, which produce large, attractive flowers, are in high demandfor gardening and commercial farming. At the Katif Center, Hippeastrumplants were grownunder controlled conditions of soil temperature, enriched carbon dioxide atmosphere, andexpanded levels of soil nitrogen and potassium. As a result of the field tests, we were able torecommend methods for enhancing bulb growth. The virus-free bulbs produced were grown

in half the time usually required for amaryllis bulb production, and were available for shippingafter only one and a half years. (Funding: Rashi Foundation)(Also, see above, Plant Physiology and Crop Development).

We are developing a conveyance method for growing vegetables in greenhouses. In thisapproach the greenhouse is divided into a contributing area, and a main growing area. Thecontributing area, where plants are grown in pots at a very high density, is relatively small.When the plants become bigger they are moved by conveyors into the main growing area,which is much larger, to accommodate the space requirements of mature plants. Thecontributing area is then ready for the next set of plants. This setup enabled us to double thenumber of growing cycles, thereby doubling the yield, and it is very labor-saving; using the

conveyance system, one or two people can maintain one hectare, reducing manpowerrequirements by 75%.

The Katif region has about 250 ha of screened greenhouses, a substantial percentage ofwhich are used to grow products marketed as insect-free. The method used is primarily theextensive application of insecticides. However, this method is not always effective, andgrowers cannot always market the produce. The heavy use of pesticides has a number ofnegative consequences: residue on produce; development of resistance to insecticides bypests; annihilation of beneficial insects and adverse effects on the plant. We are developingalternative methods to control insects which include: the use of nets and double doors ongreenhouses; adhesive strip-traps which attract the insects; and treated plastic tarpaulintraps in colors that attract insects.

Greenhouses make it possible to supply export markets with off-season produce year-round a potentially profitable aspect of desert agriculture. The conditions under which the plantsgrow inside the greenhouse will determine the quality of the product and its economicviability. We developed a computer program which adjusts climatic conditions ingreenhouses according to the needs of the plants by the use of sensing monitors. The abilityto tailor greenhouse conditions to the needs of the plants by use of heating, cooling, shadecovers, fans and humidity control, optimizes the yields while reducing manpowerrequirements.

We developed a new approach for identifying factors that influence yield levels of agricultural

products. Our method is based on state space analysis, and replaces the old random blockagricultural experimental method. We used advanced portable devices to survey the entireKatif region, and identified the advantages and disadvantages of existing agriculturaltechniques.


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Sa l i n i z a t i o n o f t h e

W a t er So u r ces i n t h e

Ga z a St r i p

I m pa c t o f Gr o u n d W a t er

Co n t a m i n a t i o n o n

A g r i c u l t u r a l

pr o d u c t i v i t y

i n Co a s t a l D eser t s:

t h e ca se o f t h e Ga z a St r i p

Pr o bl em s o f Cl i m a t e, So i l a n d W a t er , U n i q u e t o Co a st a l Deser t s

There is an essential need in any agricultural development of coastal deserts to take intoaccount the increased use of water which often leads to the salinization of fresh wateraquifers in this case, caused by over-pumping (which leads to the seepage of sea water intoaquifers), and the intrusion of fertilizers into the aquifers. Our preliminary research indicatesthat by using salt-uptake plants we will be able to reduce the amount of salt leached, and to

rehabilitate neglected soils. This method is known as phytormediation. In order to field testthe use of salt-uptake plants we are undertaking a project financed by the EEC to study theprocess of salt absorption, to define measurable parameters and to characterize a group ofplants that can be used as salt-removal plants.

In the heavily populated Gaza Strip there is an increasing demand for food and a consequentincrease in demand for water for both agriculture and domestic use. This study analyzes: 1)the process of ground water contamination from both sea water and sewage, and 2) itsimpact on agricultural productivity. The theoretical models and empirical methods beingapplied in the Gaza Strip can serve as practical tools for policy planning in coastal deserts ingeneral. The processes of desertification of coastal deserts were studied by several

Ben-Gurion University students at the Katif Center. These studies showed that the processof salinization of the ground water resulted in an increase of electrical conductivity from 0.5dS m in 1925 to 3 dS m in 1994. This increase was accompanied by a decrease of 60% of theagricultural capacity in this region.

Ka t i f Cen t er La bo r a t o r i es

Chemical Laboratory for services connected with soil solutes , water and fertilizer qualityand chemical composition. This lab operates in cooperation with the Ministry of Agriculture.

Plant Disease Laboratory for services in the identification of several diseases mainly ingeranium varieties. This lab uses a state of the art UV-microscope with a video camera,connected to a computer and self-developing image analysis software.

GCMS Laboratory In 1998, with the acquisition of a gas chromatograph massspectrometer, the Katif Center opened a lab for assessing chemical residues (mainlyherbicides and insecticides) in vegetables.

a d j u n c t st a f f

Dr. Avraham Amiel Avraham HagagAviva Cohen Mordechai ShomronZipora Cohen Uri Chayun, Head of Growers Commit teeLaura Dangian Hana Sender, Administrative ManagerDr. Avichail Grinberg

Resea r ch Pr o j ec t Lea d er s

Prof. Zvi Plaut Volcani Center Climate control in greenhousesDr. Ehud Dayan Volcani Center Climate control in greenhousesProf. Yehoshua Dayan Technion, Haifa Climate control in greenhousesProf. Beni Bar-Yosef Volcani Center FertilizationDr. Moshe Silberbush BIDR FertilizationDr. Dan Zutra Volcani Center PhytopathologyDr. Philis Weintraub Volcani Center Plant protect ion

Dr. Rami Horowiz Volcani Center Plant protectionYigal Bar-Ilan MEIGAL Plant protectionDr. Shmuel Wolf Hebrew University Bulb plants


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RESEARCH I N TERESTS

Ph.D. Hebrew University of Jerusalem, 1973; ProfessorIncumbent of the Gerda Frieberg Chair in Agricultural Water ManagementSoil-plant-atmosphere continuum under desert conditions.Phone: 972-8-659-6747 Fax: 972-8-659-6742 E-mail: [email protected]

Ph.D. Hebrew University of Jerusalem, 1989; Researcher Grade BWater movement in the soil-plant-atmospheric continuum; Energy balances of agroforestrysystems; Modeling of agroforestry systems, runoff generation and use in arid and semiaridzones; Agroforestry for firewood and fodder production in arid and semiarid zones;Optimization of runoff agroforestry systems; Microclimate of desert cities.Phone: 972-8-656-9755 Fax: 972-8-659-6757 E-mail: [email protected]

Ph.D. Ben-Gurion University, 1987; LecturerDiversity and productivity of desert plant communities as influenced by landscape structure,natural and anthropogenic disturbances, and ecosystem processes; Seed movement anddesert annual plant recruitment; Desertification, desert landscape management andrestoration; Demography of woody and herbaceous desert perennials.Phone: 972-8-659-6893 Fax: 972-8-659-6742 E-mail: [email protected]

Ph.D. Lomonosov Institute of Fine Chemical Technology, Moscow, 1977; Researcher Grade CBiochemistry of vitamins, purine nucleosides, and organometallic chemistry; Plants assources of cosmetic and medicinal products, particularly Aloe.Phone: 972-8-659-6891 Fax: 972-8-659-6704 E-mail: [email protected]

Ph.D. Tel Aviv University, 1976; ProfessorPhysiological responses of desert animals; Livestock production in the desert; Energy andwater budgets of desert animals; Reproduction and endocrinology.


Ph.D. Hebrew University of Jerusalem, 1988; Researcher Grade CRoot physiology; crop physiology; Crop simulation modeling; Soil-plant-atmosphererelationship.Phone: 972-8-659-6756 Fax: 972-8-659-6742 E-mail: [email protected]

Ph.D. Hebrew University of Jerusalem, 1969; ProfessorEcophysiology and introduction of desert plants; Seed germination, flowering, and seeddispersal strategies in desert plants of the Negev; Effects of patch disturbance andmicrohabitats in a desert community; Fast growth and vegetative propagation of succulents;Distribution of useful phenolic compounds in plants, and seasonal changes in Aloedesertspecies; Soil temperatures and plant germination; Seed banks in desert soils.Phone: 972-8-659-6890 Fax: 972-8-659-6742 E-mail: [email protected]

Ph.D. Tel Aviv University, 1980; Senior LecturerSoil fertility; Nutrient uptake by plant roots; Root respiration; Root growth; Root exudation;Nutrient uptake modeling; Effect of afforestation on soil properties; Remote sensing of soil;Tolerance to iron deficiency in strawberry cultivars.Phone: 972-8-659-6748 Fax: 972-8-659-6742 E-mail: [email protected]

Ji f t a h Be n - A sh e r

Ped r o Ber l i n e r

Ber t r a n d Bo e k en

El en a Ch a u ser - Vo l f so n

A l l a n A . D eg en

Jh o n a t h a n E. Eph r a t h

Yi t z c h a k Gu t t er m a n

M o sh e Si l b er b u sh


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PUBLICATIONS

Ephrath, J.E., M. Silberbush and P.R. Berliner. Calibration of minirhizotron readings against root length density data

obtained from soil cores. Plant and Soil209:201-208 (1999)

Berliner, P. Runoff harvesting for firewood and fodder production in Israel. Proceedings of the VI International Rangeland

Congress. Townsville, Australia 2:693 (1999)

Gozlan, S. and Y. Gutterman. Dry storage temperatures, duration, and salt concentrations, affect germination of local andedaphic ecotypes of Hordeum spontaneum(Poaceae) from Israel. Biological Journal of the Linnean Society67:163-180

(1999)

Gutterman, Y. and S. Gozlan. Afterripening, amounts of rain for germination, and seedling drought tolerance, of local and

edaphic ecotypes of Hordeum spontaneumfrom Israel. In:Evolutionary Theory and Processes: Modern Perspectives.

Festschrift in honour of Prof. E. Nevo. (Ed. S.Wasser) Kluwer, Dordrecht pp 419-439 (1999)

Gutterman, Y. Genotypic and phenotypic survival strategies of annual plant species in the Negev Desert of Israel. In:Flore

et Vegetation Tunisiennes. Vol. 8. Adaptations des vegetaux au milieu aride. (Ed. M.A. Nabli). Faculte des Sciences de

Tunis, Laboratoire de Botanique Fondamentale et Applique, Tunis. pp 151-193 (1999)

Huang, Z. and Y. Gutterman. Germination of Artemisia sphaerocephala(Asteraceae), occurring in the sandy desert areas of

Northwest China. South African Journal of Botany65:187-196 (1999)

Huang, Z. and Y. Gutterman. Water absorption by mucilaginous achenes of Artemisia monosperma: floating and germination

as affected by salt concentrations. Israel Journal of Plant Sciences47:27-34 (1999)

Krasnov, B., M. Hastr iter, S. Medvedev, G. Shenbrot , I. Khokhlova and V. Vaschenok. Addit ional records of fleas

(Siphonaptera) on wild rodents in the southern part of Israel. Israel Journal of Zoology45:333-340 (1999)

Pearlmutter, D., A. Bitan and P. Berliner. Microclimatic analysis of "compact" urban canyon in an arid zone. Atmospheric

Environment33:4143-4150 (1999)

Sauerhaft B.C., T. Thurow and P. Berliner. Spacing and green manure effects on biomass yield in an arid land water

catchment agroforestry system. Proceedings of the VI International Rangeland Congress. Townsville, Australia2:697-8 (1999)

Shem-Tov, S., E. Zaady, P.M. Groffman, and Y. Gutterman. Soil carbon content along a rainfall gradient and inhibition of

germination: A potential mechanism for regulating distribution of Plantago coronopus. Soil Biology & Biochemistry

31:1209-1217 (1999)

Shen, Z.,, Z-h. Hu and Y. Gutterman. Morphological and anatomical studies on the leaves of four species of Aloe. Acta

Botanica Boreali-Occidentalia Sinica19:688-693 (in Chinese with English Abstract) (1999)Shenbrot , G., B. Krasnov, and I. Khokhlova. Notes on the biology of the bushy-tailed bird, Sekeetamys calurus, in the central

Negev, Israel. Mammalia63: 374-377 (1999)

Spinu, M., O. Spinu and A. A. D egen. Haematological and immunological variables in a domesticated and wild subspecies of

ostrich (Struthio camelus). British Poultry Science40:613-618 (1999)

Weil, S., A. A. Degen, M. Friedlander and A. Rosenstrauch. Low fertility in aging roosters is related to a high plasma

concentration of insulin and low testicular contents of ACTH and lactate. General and Comparative Endocrinology

115:110-115 (1999)

Weil, S., I. Rozenboim, A. A. Degen, A. Dawson, M. Friedlander and A. Rosenstrauch. Fertility decline in aging roosters is

related to increased testicular and plasma levels of estradiol. General and Comparative Endocrinology115:23-28 (1999)


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Tech n i c a l st a f f

Sec r e t a r i a l s t a f f

V i si t i n g Sc i en t i st s

Po st d o ct o r a l f el l o w s

Gr a d u a t e St u d e n t s

W y l e r D ep a r t m en t o f D r y l a n d A gr i cu l t u r e

Suliman Abu-ZaabutShlomo FeingoldJoseph GoldsteinMichael Kam

Lilia MedvedevDavid MezigClaudio Wexler

Frieda GilmourOdette Levi

Carol Baskin, University of Kentucky, USAJerry Baskin, University of Kentucky, USADerek Bewley, Guelp University, CanadaImre Friedman, Flor ida State University, USASerra Hepaksoy, EGE University, Turkey

Zhenghai Hu, Northwest University, ChinaBatyr Mamedov, National Institute of Desert Flora and Fauna, TurkmenistanJoachim Pretz, Large Scale Plant Project, GermanyQiuyun Qu, ShaanXi Research Institute, ChinaKonstantin Rogovin, Russian Academy of ScienceProf. Michael Barbour, University of California at Davis, U.S.A.Prof. Costas Thanos, University of Athens, Greece.Prof. Johannes van Staden, University of Natal, Pietermaritzburg, South AfricaProf. Jan Hoorweg

Adit Arazi, Hebrew University of JerusalemPatricia Figuerola, University of Buenos Aires, Argentina

Avner AnavaHadasa CohenShirley Cohen-GrossKlaus DroppelmanEmilio GarciaZhenying HuangEfrat JoelBat-Sheva KelhamerFan LingNurit N in-AriShachar Shem-TovZonggen Shen

Zhao WenguangEbru YasaWalter ZegadaZhang ZhenMeirong Zhou


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Al ber t Ka t z

Depa r t m en t o f D r y l a n dB i o t e c h n o l o g i e s

Virus-free potato

plantlets, produced

in the tissue culture

and propagation

laborator ies, support

local farmers.

Clockwise from upper left:

Integrated polyculture

system for intensive

dryland aquaculture.

Plant tissue culture

laboratory carries out

independent research in

tissue culture and

micropropagation of plant

tissue in projects relevant

to desert agriculture.

Astaxanthin accumulation

in Haematococcus is induced

by environmental stress

conditions that inhibit cell

growth, causing a morpho-

logical and biochemical

transformation, turning

normally green, motile cells

into inert red cysts.


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Al ber t Ka t zDepa r t m en t o f Dr y l a n dBi o t ech n o l o g i es

Prof. Sammy Boussiba, Chairperson

The discipline of biotechnology employs living organisms (or parts of organisms) to make ormodify products, and develops techniques for altering living organisms for specific uses. Itoffers efficient and cost-effective methods for producing an array of novel value-addedproducts. Biotechnology is of special value in arid lands, where special adaptations arenecessary, as traditional or conventional methods of agriculture are difficult or impossible toimplement.

Scientists at the Albert Katz Department of Dryland Biotechnologies investigate the natureof life and ecosystems at the molecular level in order to improve production methods anddiagnostic tools used in arid-land development. In pursuing this research, our approach is

based upon the sustainable development of desert regions. Some of the biotechnologiesdesigned in the Katz Department have potential for increasing food production, reducing thedependence of agriculture on environmentally damaging chemicals, lowering the cost of rawmaterials, and reducing the ecological impact of traditional manufacturing processes.


ACADEM I C STAFFAppelbaum, SamuelBirnbaum, ElliottBoussiba, SammyCohen, ZviGale, JosephGolan-Goldhirsh, AviGuy, MichaHeimer, Yair M.Levi, ShalomLips, S. HermanRichmond, AmosVolokita, MichaVonshak, Avigad

ASSOCIATE STAFF

Khozin-Goldberg, InnaOrlovsky, NicolaiWolwich, Liobov (Luba)

A flat, modular photobioreactor

for m ass cultivation of

microalgae, constructed fromtransparent glass. The dense,

deep green algae culture between

glass plates gives the modules

their dark color.


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Ef f ect o f w a t er

t e mper a t u r e o n g r o w t h

a n d su r v i v a l o f

Lit o p en a eu s v a n n a m ei

po st l a r v a e a n d j u v en i l e s

r ea r ed in g eo t h e r m a l

br a c k i sh w a t e r

A ppel bau m

RESEA RCH A CTI V I TI ES

AQUa CULTURE

In the aqualculture laboratory researchers investigate the biology, nutrition, and behavior offish. New and improved aquaculture equipment and techniques have been developed, manyof which have commercial applications. Environmentally and ecologically appropriatecommercial enterprises are being designed and established, using systems which areaffordable for even the small-scale fish farmer. Under study are carp, eel, Tilapia, catfish, seabream, barramundi, shrimps, and ornamentals. Research and development emphasize thedesign of low-cost, simple devices which require little maintenance and retain water qualitywithout use of excessive amounts of water. The group provides active assistance in theestablishment of fish farms utilizing the unpolluted brackish water of the Negev desert, andis involved in high-density fish husbandry in closed systems.The laboratory also provides a regional fish veterinary service and carries out research on:(a) Pasteurell (pseudotuberculosis), a gram-negative bacterium(b) Oodinium, a dinoflagellates parasite(c) Mycobacterium, a gram-positive bacterium.

This study was undertaken to determine the effect of three water temperatures, 26, 31and 36C, on growth, feeding and survival rate of Litopenaeus vannamei postlarvae andjuveniles of three sizes. The postlarvae and juveniles were stocked at a density of 710 PL/m2and reared indoors in brackish water of 3ppt salinity. The experiment was divided into three

trials, each with three different feeding regimes. The dry feed used in the trials was acommercial, dry shrimp feed (Zeigler Bros, USA, crude protein 45-50%, crude fat 15%). Intrial I (63 days), postlarvae of initial body weight x=0.0600.32g, received dry feed only. Intrial II (35 days), postlarvae of initial body weight x=0.060+0.21g, received freeze dried cellsof the algae Nannochloropsis sp(moisture 8-10 %); and in trial III (28 days), postlarvae of initialbody weight x=0.946+0.23g, received a combination of 80% dry feed and 20% freeze driedNannochloropsiscells. The dry shrimp feed was given manually four times a day at the feedingrate recommended by the feed manufacturer. Growth and survival rates for postlarvae andjuveniles were significantly higher (p>0.05) at 31C than at the other temperatures. Weeklygrowth rate of the postlarvae and juveniles reared at 31C was found to be the highest(0.675+0.454g). Food conversion ratio remained lower at 31C than at 26and 36C.

Furthermore, 36C negatively affects the survival rate and specific growth rate of juvenileslarger than 2 g.

Sea bass (Lates calcarifer) is one of

the species being introduced into

a rearing chain in this integrated

polyculture system .


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I n t r o d u c t i o n o f t h e sea

b a ss (La t es ca l ca r i f er )

i n t o I sr a e l i d e ser t

a q u a c u l t u r e

A ppel bau m

D ev el o p men t o f a

po l y cu l t u r e t e ch n o l o g y

su i t a b l e f o r d e ser t

c o n d i t i o n s

A p pel b a u m

A n o v e l , si n g l e- st a g e

p r o cess f o r t h e r em o v a l

o f n i t r o g en f r o m

w a s t e w a t e r

A p pel b a u m

The sea bass (Lates calcarifer), has recently been introduced into our laboratory fromAustralia for study. The sea bass, (also called barramundi), is raised in open ponds and seacages in southeast Asia and Australia, where it is considered a high quality fish. In general,sea bass are opportunistic predators throughout their life cycles. However, in captivitythey readily accept pelleted food. This euryhaline fish needs warm water for acceleratedgrowth and is therefore most suitable for desert aquaculture. Our preliminary

observations indicate fast growth at 28C to 29C; fish reach a table size of approximately0.5 kg from fingerlings in about 6 to 7 months. However, the sea bass is a very sensitivefish needing high water quality and most careful handling. Larger fish are prone to gradingand transport damage. In addition, the sea bass is a viscious, cannibal which, in captivity,can cause high losses by feeding on its own siblings. The investigations on the sea bass areconcentrating on: (a) Introduction of yolk sac larvae (TL 2.0) and their rearing underintensive conditions by shortening the use of live food and extending the use of dry feeds;(b) Feeding strategies under different light conditions at postlarval stages to minimizelosses caused by cannibalism; (c) Artificial reproduction via induced spawning, incollaboration with a marine station; (d) The position of sea bass in an integratedpolyculture system.

Under the project 'integrated polyculture system', a study is being conducted on the use ofthe introduced sea bass and other species into a rearing chain where the water effluent froma tank holding one species flows to a tank holding another species which can utilize theorganic material suspended in the water. Our preliminary observations clearly indicate thatby growing various fish species in a chain, each species at a high stocking density in differenttanks, one species can benefit from the other when tanks are placed in the proper sequence.The suspended organic material of one species, which is otherwise wasted, is, in this way,utilized by the other species, reducing feed costs and minimizing environmental pollution bythe water effluent from the system.Our Fish Veterinary Laboratory will investigate the health impact of one species on theothers in the chain, as, though kept separately, one species could be detrimentally affected

by another via the permanently circulating water.

On the basis of NO2 discharges into the wastewater and the retention of activemicroorganisms, the University of Hamburgs Department of Microbiology developed anovel, single-stage process for the removal of nitrogen from wastewater with a highammonium load. The technology is based on lithoautotrophic ammonia-oxidizing bacteriathat are capable of active removal of ammonia from the water. A mobile, 2m3 pilot plant wasoperated in an intensive fish rearing system in the aquaculture laboratory. After severalmonths of operation with effluent water heavily loaded with ammonia from the fish growingsystem, 80% of the ammonia could be removed.

BIOSTRESS RESEARCH

Work in the Biostress Research Laboratory focuses on the productivity of crops and otherplants under suboptimal conditions characteristic of arid lands. We are probing themechanisms of plant adaptation at the physiological and molecular levels, with the aim ofproviding rapid screening methods for wild and cultured stress-tolerant genotypes, and topinpoint specific genes capable of enhancing sustained crop production in stressfulenvironments. The effects of stress on various enzymes and cellular organelles are beinginvestigated in roots, shoots, and developing seeds. We are applying these basic studies tospecific problems of crop production in arid areas. Research is funded by a number ofinstitutions, including US-AID (US Agency for International Development), GIF

(German-Israel Binational Fund), ICA-Israel, BSF (US-Israel Binational Science Foundation),Israel Ministries of Science and of Agriculture, EU-INCO (European Union INCO-COPERNICUS program), and the Fohs Foundation.


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M o l ecu l a r m ech a n i sm s

o f s t r e ss- en h a n c ed A BA

pr o d u c t i o n

Lips

Cl o n i n g o f b a r l e y AO

g e n e s

Vo l o k i t a , Li ps

Su b st r a t e sp ec i f i c i t y o f

A O p r o t ei n b a n d s a n d

st r e ss- i n d u c e d

en h a n cem en t o f A O

t r a n scr i pt .


St r e ss- i n d u c e d cy s t e i n e

sy n t h esi s i n t w o p l a n t s

po t en t i a l l y u sef u l f o r

ph y t o r em ed i a t i o n

Lips

Aldehyde oxidase (AO) is required for the production of ABA under stress conditions.Previous work has shown that the level of the enzyme increases upon application of stress(salinity or drought) and when ammonium is the sole N source in the nutrient medium.Work has been carried out to determine the mechanism of AO gene activation by stress andammonium. It was determined that the 3 main isoforms of AO are composed of twodifferent monomers, each of them produced by a different gene, which are being cloned at

the moment. Actual synthesis of ABA correlates with the production of the three isoforms,contrary to the situation under nonstress conditions when only one of the AO bands isclearly evident and the other two yield faint activity bands.Work has been carried out to determine the mechanism of AO getion products.With: R. Omarov, Bach Inst. of Biochemistr y, Moscow.

Molecular cloning and sequencing of a cDNA fragment of 850 bp encoding barley AO havebeen performed using sense and antisense degenerate primers designed by deduced aminoacid sequences of known aldehyde oxidases from bovine maize. The cDNA library ofammonium grown plants was constructed and subsequently screened. Eight single plaqueswere isolated giving a positive signal. These were used for the in vivoexcision to transfer theinsert in a plasmid. The digestion of these with restriction enzymes (EcoRI, XhoI) gaveinformation on the size of the cloned inserts. 6 different clones with an insert size between1 3 kb were isolated . Full-length AO genes sequence is currently being performed.With: R. Omarov, Bach Inst. of Biochemistry, Moscow; R.Tischner, Inst. of Gottingen, Germany

Substrate specificity of AO protein bands in native gel after PAGE was determined usingseveral aliphatic and aromatic aldehydes. It was shown that abscisic aldehyde was apreferential substrate for two AO isoforms in barley roots. The activity of abscisic AO wasalso found in roots and leaves of barley. Subunit composition of AO dimers and molecularweight were estimated by SDS-Western blot procedure using polyclonal AO specificantibodies.Ammonium grown plants revealed a higher level of AO transcript as compared to nitrate-fed

plants. Roots of ammonium-fed plants contained considerable levels of three AO bands afterPAGE (AO2, AO3 and AO4) of which nitrate-fed plants exhibited only traces. Western blotsrevealed enhanced levels of AO proteins in extracts of ammonium-grown plants. Weconclude that ammonium enhances the transcription of the gene-coding for two unequalmonomers of the AO enzyme.With: R. Omarov, Bach Inst. of Biochemistr y, Moscow.

Two ubiquitous plant species: Phragmites australis(Cav.)Trin ex Steud and Typha latifolia(L.)were used in our experiments (performed with intact plants and/or detached leaves) theobjective of which was to study the effects of stress conditions on cysteine synthase (CS oro-acetylserine thiol lyase - OASTL) activity and some possible related metabolic andprotective pathways in plants. The synthesis of cysteine represents the final step of sulfurassimilation and also is the almost exclusive entry of reduced sulfur into organic compoundsin plants. Thiolic compounds are clue factors in stress defense mechanisms.Cadmium (0.1- 100 M) and salinity (100 mM) as well as NH4

+ 2mM (as nitrogen source)induced OASTL activity. In detached Typhaleaves the response was very significant in short-time Cd treatments (2, 4, 6 h) and later decreased gradually (8, 24, 48 h). The response wasmaintained 48 h at a higher level in Cd treatedPhragmitesas compared to controls, but lowerthan Typha. The induction of OASTL activity in intact plants was significant after 3 daystreatment in roots and, after 1 week, in shoots too. Salt stress and NH4

+ induced OASTLactivity in Phragmitesintact plants, mainly by NaCl. Changes in the GSH (a cysteine containingtripeptide) pool of Typhaplants correlated inversely with the activity of OASTL. Theseresults are also consistent with the finding that plants overexpressing cysteine synthase do

not significantly accumulate GSH. Previous results showed that the total reduced thiol poolin Typhaplants increased very significantly in Cd stress. Considering that the differencebetween total reduced thiol and GSH suggest its incorporation into phytochelatin (PC) and


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101

Bi o d i v e r si t y :

g er m in a t i o n a n d

g r o w t h o f l eg u m in o u s

pl a n t s (On o br i ch is

t r a n sca u ca sica a n d

Ast r a ga l us v il l a sim u s) o f

t h e Ky z i l Ku m d eser t i n

U z b e k i st a n

Lips

Bi o d i v e r si t y : i so l a t i o n

a n d ch a r a c t e r i za t i o n o f

sa l t t o l er a n t N -f i x in g

b a c t er i a sel e ct ed i n t h e

K y z i l K u m d e ser t o f

U z b e k i st a n

So a r es, Lips

we assume that Cd binds very rapidly free GSH in Cd-thiol complexes (PCs). We have foundalso enhanced expression of aldehyde oxydase (AO) in Phragmites, while this enzyme was notdetectable in Typha. This result suggests that a) OASTL could act as the sulfurylase requiredfor the activation of AO or b) Both sulfurylating enzymes are regulated by similar factors(NH4

+, salinity, and heavy metals). We have started the extraction of total RNA from testplants in preparation for cDNA probes (for OASTL) amplification needed for northern

blotting assay in the future, to study the effects of stress conditions at the transcription ofOASTL.With: Erica Fediuk, University of Cluj, Romania.

Germination of Astragalus villassimus: Several germination pretreatments were used: H2SO4,boiling water, KNO3, gibberellic acid, temperature fluctuations and combined treatments.Several supports were used: filter, sea sand, dune sand and vermiculite. None of thesemethods yielded positive results. After an apparent beginning of germination, root growthstopped and the seed died.Germination of Astragalus villassimus: Several germination pretreatments were used: a)H2SO4; b) boiling water; c) treatments with KNO3. After all these treatments it turned outthat the seeds germinated best with distilled water, contrary to their initial behavior. Weconcluded that with dormant seed, optimal germination was achieved after pretreatment for1h in H2SO4 followed by 0.02 mg/ml gibberellic acid. When the seeds were not dormant,distilled water was enough to obtain a germination rate of 90-100%.Growth of Onobrychis transcaucasica: Seedlings were transferred to vermiculite and westudied their subsequent development. Four types of nutrient solutions and different kindsof supports were tested. Onobrychis plants do not survive in mixed support that containslocal soil. The best support was 1:1 (v/v) vermiculite and organic soil. It is too early to seeresults of the nutrient solutions used: 4 mM NO 3, 2 mM NH4NO 3, 1mM NH4NO 3, nonitrogen sources. The low concentration (1mM) mixed nitrogen source may be the best forgrowth of these seedlings.Alexender Fediuk, University of Cluj, Romania

Selection of isolates: A large collection of nodule bacteria was isolated from root nodulesof leguminous shrubs and trees growing in the Kyzil-Kum desert (Uzbekistan). From thiscollection, a total of 219 isolates from different nodules were used to select salt tolerantsymbiotic nitrogen fixing nodule bacteria for further studies. Bacteria were isolated from (a)Amodendrum connollyi(sandy Acacia). Leguminous tree. 50 isolates. (b) Astragalus unifoliolatus.Leguminous shrub. 62 isolates. (c) Astragalus vilosissimus. Leguminous shrub. 107 isolates. Inorder to select appropriate bacteria for further studies, the bacteria were tested for thefollowing: (a) The presence of nif, a gene essential for nitrogenase. (b) The presence of nod,the gene that establishes the symbiotic association, and (c) their capacity to grow in a highsalt concentration.Nifand nodgenes: This test represents a molecular approach to assess whether thebacteria will be capable of establishing symbiotic nitrogen fixation. The test is necessary sinceit is very frequent to isolate soil rhizosphere bacteria during isolation of nodule bacteria,even though nodules are sterilized before isolation of bacteria. Presence of these genes wasassessed by hibridization of total DNA from bacteria to labeled DNA probes. The DNAprobes chosen were the following: (a) nifHDKgenes. These are the structural genes for theenzyme nitrogenase, which are highly conserved among free living or symbiotic nitrogenfixing organisms. These genes from Klebsiella pneumoniae. (b) nodABCgenes. These are theso-called common nodgenes, which are the most conserved nodgenes among nodulebacteria. These genes come from Rhizobium meliloti. The 219 isolates were analyzed by thisprocedure. Using the nifprobe, 88 isolates produced a positive signal in the screening, whilejust 71 were considered as positive in the screening using the nodprobe.

Salinity: Out of the 219 initial isolates, 15 strains were found able to grow on solid mediumcontaining 1.25 M NaCl or higher, which produced a positive signal with both the nifand thenodprobe. All of them grew fast in liquid medium, with a doubling time between 21 and 35


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102

D et er m i n a t i o n o f si t e s o f

A BA sy n t h e si s i n m o n o

a n d d i co t y l ed o n e s i n

r e sp o n se t o s t r e ss

Lips

Ro o t t o sh o o t

i n t er ch a n g e o f sl o w

d o w n a n d sp eed u p

s i g n a l s

Lips

cDN A o f b a r l ey r o o t s


min. Of these selected strains, 4 were isolated from Amodendrum connollyi (sandy Acacia)nodules, 4 from Astragalus unifoliolatus, and 7 from Astragalus vilosissimus. The selected strainswere used for further studies.Strain characterization will continue. Determination of whether the different strains fromeach plant are really different or they are just "brothers" will be carried out.With: S. Khakimov, Z. Shakirov, Academy of Science, Tashkent, Usbekistan; E. Santero, Univ. of Sevilla, Spain

Aldehyde oxidase (AO) is a key enzyme in abscisic acid biosynthesis, a hormone regulatinggrowth and development of plants especially under stress condit ions. Changes of AO activityas well as organ distribution of AO gel electrophoretic bands were analyzed in somemoncotyledons (barley, maize, ryegrass) and dicotyledons (pea, tomato) species undersalinity, ammonium and nitrogen deficiency treatments. Increases of AO activity after stressapplication were observed mainly in leaves of dicots and roots of monocots. Activation ofAO during stress is characterized by the production of multiple isoforms (polymorphism),one of which seems to have an especially high affinity for abscisic aldehyde, the substrateoxidized by the enzyme to ABA. Studies on organ specific distribution of AO activity showedthis AO polymorphism in gel electrophoretic bands in roots (3 bands) of monocots orshoots (3 bands) and shoots (3-1 bands) of dicots. The characteristic proliferation of AO gelelectrophoretic bands in response to stress which occurs in roots of barley, maize andryegrass (monocots) and leaves of tomato and pea (dicots) may be indicative of the main siteof ABA synthesis in stressed plants.With: E. Zdunek,Warsaw Agricultural Univeristy, Poland

Plant adaptation to stress is mediated by interacting multiple signaling pathways thatcoordinate growth and primary assimilation activities of shoots and roots. Abscisic acid(ABA) and cytokinins are plant hormones that act as signals of distress and wellbeing,respectively, describing the activity status of the root. Changes of the concentration andxylem loading rates of ABA and cytokinins in response to salinity, ammonium and nitrogendeficiency in pea plants were studied. Increase of ABA xylem delivery rate during early stage

of stress response was observed only in salinity treatment (50 and 100 mM NaCl).Ammonium and low nitrogen treatments produced a reduction of cytokinin supply by theroots but little change in the level of ABA export by the root through the xylem. The signalsdefining the capacity of the root to supply water and nutrients to satisfy the growth potentialof the shoot may also include the balance between organic and inorganic nitrogencompounds in the xylem sap. A low organic/NO3- ratio in optimal growth conditionschanged under all stress condition to a high organic N/ NO3- ratio.With: E. Zdunek, Warsaw Agricultural Univeristy, Poland

Starting with total RNA, mRNA was isolated. Cloning was carried out with a Stratagen kit.After receiving a high titer of cDNA-library, amplification was performed and screeningresulted in 8 isolates that were screened in a second round. These were used for in vivoexcision to transfer into plasmids resulting in 32 isolated colonies. Digestion of these withappropriate restriction enzymes gave initial information on the size of the cloned inserts. Atleast 6 different clones with inserts ranging between 1-3 kb have been isolated and will besequenced shortly.With: R. Omarov, Bach Inst. of Biochemistry, Moscow; R. TischnerUniv, of Gottingen, Germany


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103

Th e beh a v i o r o f f l a c ca

t o m a t o m u t a n t s i n

g r a f t i n g e x per i m en t s

Sa gi , Lips

X y l e m sa p ch a n g es i n p Ha n d co m p o si t i o n

t r i gg er ed b y sa l i n i t y

Sa gi , Lips

Grafting experiments were carried out to investigate the interactions between shoots androots of the flacca tomato (Lycopersicon esculentum) mutant with those of the wild type. Theflacca genotype is an ABA-deficient wilting mutant, characterized by high stomatalconductance during day or night, high transpiration rate, marked tendency to wilt, andlimited biomass production. Flacca scions grafted on to wild-type root stocks (Fs / Wr)exhibited higher ABA levels, lower transpiration rate, higher water content and slightly

higher dry weight production rates than those of control grafts (Fs / Fr ), but still with lowerABA level, xylem exudate rate, ABA xylem loading rate, and dry weight production than thewild-type control grafts (Ws / Wr ). Flacca root stock grafted on to wild-type scion (Ws /Fr) showed higher ABA level, xylem exudate rate, ABA xylem loading rate, dry weightproduction and length than Fs / Fr. It did not bring about significant changes in the wild-typescion comparing with Ws / Wr.The growth of flacca root was increased to the level of wild type roots, while its shootgrowth was not significantly enhanced in reciprocal grafts. However, in double grafts, flaccascion and wild-type scion grafted on to flacca rootstock (Fs+Ws / Fr ) or wild-type rootstock(Fs+Ws / W r ), flacca shoot growth in fresh weight was significantly enhanced.Conclusions:

a) W s/Fr the shoot growth is much higher than Fs/Fr, meaning that Fr can support Ws.b) Ws/Fr root growth greatly improved, meaning Fr growth is better when supported by

Ws than by Fs.c) Ws sends to the Fr a factor other than ABA that releaved growth inhibition of the flacca

root.d) Fs/Wr - Endogenous ABA of Wr seems to accumulate and inhibits wild type root

growth, at the same time improving Fs growth.e) Root ABA increased water uptake or decreased root resistance to water transport.f) Endogenous ABA transport could be observed from shoot to root and from root to

shoot.With: C. Guaziong, Ben-Gurion University

Xylem sap changes in pH and composition were studied in tomato plants. The workinghypothesis is that a rise in xylem sap pH, reflecting composition changes, and signals waterdeficiency in the roots to the shoot and reduces water loss by transpiration via stomata. Thetomato mutant, flacca, has a shortage of ABA and is not able to close stomata. Flacca plantswere used in the experiment to mimic the conditions of water deficiency in plant rootswithout actually exposing the plant to stress. Exposing tomato plants to drought by stoppingirrigation caused a rise in xylem sap pH from about 5.2 to 5.8 over 5 days. The total cationconcentration of the xylem sap increased significantly during drought development. Totalcation concentration of xylem sap in the flacca plants was two-fold higher than that inwild-type plants under well-watered conditions. Exposure to salinity did not cause a rise butrather a drop in xylem sap pH of tomato plants even if the plants suffered from waterdeficiency as indicated by the lower leaf water potential and plant transpiration. Accordingly,salinity did not cause a drop in the rate of stomata opening over a day-night observation. Onthe other hand, the flacca root system had a lower xylem sap flux rate than that of thewild-type plants, expressed on a plant or a unit root length. It is concluded that a rising xylemsap pH signals root water deficiency under drought conditions but not salinity conditions.Transpiration decrease by salinity is a result of lower leaf water potential rather thandecreased stomata opening.With: X. Fu, Ben-Gurion University


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Reg u l a t i o n o f c y t o k i n i n

o x i d a se i n r o o t s o f

p l a n t s g r o w n i n

a m m o n i u m (sl o w

g r o w t h ) o r n i t r a t e (f a st

g r o w t h )

Lips

P h y t o r e m e d i a t i o n :

Th e r eg u l a t i o n o f

p h y t o c h e l a t i n

sy n t h esi s a n d

a c cu m u l a t i o n i n

p l a n t s

Lips

Ca d m i u m u p t a k e a n d t h e

i n d u c ed p r o t ec t i v e

m e ch a n i sm s i n t w o

w e t l a n d sp ec i es,

Ph r a gmi t es a ust r a l is

a n d Ty ph a l a t if o l ia

Lips

The transport of cytokinins and ABA shows a considerable correlation with the growth rateof plants. Under stress conditions the xylem cytokinin flux is almost completely eliminatedwith the concomitant increase of ABA. The reverse situation may be observed infast-growing plants under suitable environmental conditions. At the same time, the pools ofABA and cytokinins in the roots of the stressed plants remain remarkably steady, suggestinga tight regulation of the pool size through the balance of synthesizing and oxidizing events.

Much has been learned recently about the synthesis of ABA and cytokinin but less is knownabout the regulation of oxidizing enzymes affecting these hormones. This recently-begunstudy follows changes in the activity and molecular levels of the enzymes oxidizing ABA andcytokinins during stress (salinity and drought) and in plants grown in ammonium or nitratenitrogen sources.The research included the following studies: (A) Study of cytokinin oxidase activity andcytokinin content (trans-zeatin riboside) in the roots and leaves of barley seedlings independence with time course in the presence of nitrate ions; (B) Study of cytokinin oxidaseactivity and cytokinin content (trans-zeatin riboside) in different organs of barley seedlings asa function of time course and as affected by ammonia ions; (C) Elucidation of the role ofcytokinin oxidase in the regulation of phytohormone content in barley seedlings grown innitrate and ammonia in combination with salinity; (D) Investigation of the glycosylationpattern of cytokinin oxidase by using Con A-Sepharose 4B column chromatography. (E)Purification of the cytokinin oxidase of the barley seedlings and study of the catalyticproperties of the enzyme.With: I. Yakubov, Institute of Microbiology, Tashkent, Uzbekistan

Some plants respond to exposure to heavy metals by producing SH-rich polypeptides(phytochelatins) with the capacity to bind heavy metals such as Cd, Cu, and Zn. We haveestimated the level of GSH synthesis in roots and leaves of pea and barley as the precursorof phytochelatins during different growth period t reatments with different concentrations ofheavy metals. The content of phytochelatins was measured by atomic absorption. Cadmiumwas a stronger inducer of metal-binding peptides than Cu and Zn. The phytochelatins (PCs)

appear in both plants after 2-3 days by treatment of Cd, while synthesis of PCs aftertreatment with Cu and Zn occurred after 1 week. The highest level of phytochelatins wasfound in roots of barley and pea. Pea plants had a higher level of Cd ion accumulation thandid barley. The partially purified (PAGE) cadmium-binding complex isolated from pea rootsby gel-filtration on Biogel P30 had an apparent molecular weight of about 6 kD. This projectfocuses on conditions suitable for the optimization of phytochelatin synthesis and chelationand absorption of heavy metals.With: V. Kuzovlev, Kazak State University, Kazakhstan

Waterways and wetlands are often contaminated by heavy metals, which may stay andaccumulate therein. A challenging task for phytoremediation technology is the use of plantsfor the removal of toxic metals from the environment. Our objectives were to test theability of two wetland plant species (Phragmites australis(Cav.) Trin. ex. Steud and TyphalatifoliaL.) to accumulate cadmium in roots, its translocation to shoots and the defensemechanisms induced by Cd2+, at the levels of thiol metabolism and antioxidant enzymeactivity.About 90% of the Cd2+ taken up was retained in roots of Typha, while essentially notranslocation to the shoots occurred in Phragmites. In the roots, accumulation in cattail was3-fold higher than in reed, reaching 30 mg/gDW, in contrast to 10 mg/gDW in reed. Ingeneral, the accumulation of the toxic metal in the root correlated well with the increase offree thiol content and with the stimulation of glutathione reductase activity. Comparing thetwo species, reduced thiol synthesis in the roots was higher in Typha than in Phragmitesresulting in concentrations of about 30 mole/mg protein and 4.5 mole/mg protein,

respectively. Glutathione reductase activity was extremely low in Typha (0.04 EU/mgprotein) in contrast to 3.0 EU/mg protein in Phragmitesresulting in an undetectable level ofthe oxidized form. Since for thiol (cysteine) biosynthesis the reduced sulfur availability may


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Th e i n t r a c el l u l a r

l o c a l i z a t i o n o f

a l d e h y d e o x i d a se in

pl a n t r o o t s

Lips

A l d e h y d e o x i d a se

d i st r i bu t i o n i n m a i z e

r

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5th Dryland Agriculture

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